I'll accept Eucnemesaurus but not Aetonyx since it's a Jurassic species and not a Triasic one. The two dino's I'm thinking of are some of the most famous triasic dino's. (You only need to guess one, of course)
I heard rumors about Dimetrodon being reconsidered as a herbivore rather than a carnivore. Personally I'd have to know more details to give a judgement on that theory. Dimetrodon's teeth sure don't look like they were made for food that doesn't twitch anymore. Anyway, is Dimetrodon the species you are refering to?